Curiosity Finds A Former Lake On Mars
Popular Science

Once upon a time, in the lowest part of Gale Crater on Mars, there was a lake about the length and width of one of the Finger Lakes in upstate New York. It was fed by rivers that ran into it. If you stood on its shores, you might have seen snow or ice capping the mountains in the distance.
After its first 100 Mars-days, or sols, on the Red Planet, NASA’s Curiosity rover trundled down into this now-dry lakebed. The rover took images of rocks along the way and drilled two holes to take samples. It’s from these samples scientists determined this lake existed and that its waters weren’t too alien, after all, compared to water on Earth. The water was of relatively neutral pH and low salinity. “I would be pretty confident it would be fresher than seawater,” says Scott McLennan, a geoscientist with Stony Brook University in New York who worked on this and other studies based on Curiosity data.
This is water that microbes could have lived in, although Curiosity found no direct evidence of life on Mars, nor is it designed to do so, McLennan tells Popular Science.